枚举

Teacher YYF(POJ-3746) 题面 As we all know, grammar is very important when learning English. Now, YYF become a teacher of a primary school. The students are good at memory so they can tell the meaning and the function (noun, verb …) of the words in the textbook. But, they cannot use these words properly. In YYF’s mind, writing sentences is a good way to learn grammar. So he tells the student to write 20 sentences a day, using the word learned in the class. As YYF has a lot of student, he will receive many sentences from his student. What a horrible work to check all the sentences. You are one of YYF’s friends, so he asks you for help. You task is to write a program to check the sentences. ...

Fliptile (POJ - 3279) 题面 Farmer John knows that an intellectually satisfied cow is a happy cow who will give more milk. He has arranged a brainy activity for cows in which they manipulate an M × N grid (1 ≤ M ≤ 15; 1 ≤ N ≤ 15) of square tiles, each of which is colored black on one side and white on the other side. As one would guess, when a single white tile is flipped, it changes to black; when a single black tile is flipped, it changes to white. The cows are rewarded when they flip the tiles so that each tile has the white side face up. However, the cows have rather large hooves and when they try to flip a certain tile, they also flip all the adjacent tiles (tiles that share a full edge with the flipped tile). Since the flips are tiring, the cows want to minimize the number of flips they have to make. ...